title: Radiofluorination of diaryliodonium tosylates under aqueous-organic and cryptand-free conditions.
abstract: Positron emission tomography (PET) has growing importance as a molecular imaging technique in clinical research and drug development. Methods for producing PET radiotracers utilizing cyclotron-produced [(18)F]fluoride ion (t1/2 = 109.7 min) without the need for complete removal of irradiated target [(18)O]water and addition of cryptand are keenly sought for practical convenience and efficiency. Several structurally diverse diaryliodonium tosylates, XArI(+)Ar'Y TsO(-) (X = H or p-MeO), were investigated in a microfluidic apparatus for their reactivity towards radiofluorination with high specific activity (no-carrier-added) [(18)F]fluoride ion in mixtures of DMF and irradiated target [(18)O]water in the absence of cryptand. Salts bearing a para or ortho electron-withdrawing group Y (e.g., Y = p-CN) reacted rapidly (∼3 min) to give the expected major [(18)F]fluoroarene product, [(18)F]FArY, in useful moderate radiochemical yields even when the solvent had an [(18)O]water content up to 28%. Salts bearing electron-withdrawing groups in meta position (e.g., Y = m-NO2), or an electron-donating substituent (Y = p-OMe), gave low radiochemical yields under the same conditions.
authors.affiliation: Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Joong-Hyun
authors.initials: JH
authors.lastname: Chun
authors.forename: Sanjay
authors.initials: S
authors.lastname: Telu
authors.forename: Shuiyu
authors.initials: S
authors.lastname: Lu
authors.forename: Victor W
authors.initials: VW
authors.lastname: Pike
mesh_terms: D001557:Benzenesulfonates / Q000737:chemistry*; D004988:Ethers, Cyclic / Q000737:chemistry*; D005462:Fluorine Radioisotopes / Q000737:chemistry*; D015394:Molecular Structure; D009861:Onium Compounds / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000737:chemistry; D012545:Schiff Bases / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: C573194:4-methylbenzenesulfonic acid; D001557:Benzenesulfonates; D004988:Ethers, Cyclic; D005462:Fluorine Radioisotopes; D009861:Onium Compounds; D009930:Organic Chemicals; D019275:Radiopharmaceuticals; D012545:Schiff Bases; C444241:cryptand; D014867:Water